CN1089414C - New-type safety valve - Google Patents

Abstract

The present invention provides a novel safety valve which is an indirect-action type safety valve belonging to an overpressure protecting device. The novel safety valve comprises a main valve, a subsidiary valve and a release operating valve which are separately arranged, wherein the main valve is installed in a positive direction, the subsidiary valve is installed in a reverse direction; a pulse tube passes through the part between the main valve and the subsidiary valve; a capture type filter is connected in series with the inside of the pulse tube and is connected with a release control valve into integration. The main valve and the subsidiary valve are both non-leakage safety valves. The release operating valve can be a manual valve, an electromagnetic valve, or a pneumatic valve. The present invention has the advantages of simple structure, low manufacturing cost, stable performance and long service life.

Description

New-type safety valve

1, technical field

The present invention relates to safety valve, the indirect acting type safety valve that particularly main and auxiliary valve branch is arranged.

Safety valve is the requisite overpressure protection equipment of pressurized container or system that all inside fill the changeable pressure medium.

The object of the present invention is to provide a kind of being used in particular for the light-water is the novel indirect acting type safety valve of nuclear reactor overpressure protection system of reactor coolant, and its working principle as shown in Figure 1.When the valve inlet pipe is chewed when containing pressure medium water or steam, medium makes main valve clack [2] produce a power that makes progress, it constitutes sealing force between main valve clack [2] and the main valve seat [49] together with main valve preloading spring [7] to the active force of main valve clack [2], and this power increases (see figure 3) with system pressure.Meanwhile, enter auxilliary valve body [30] interior water or steam by pulsed tube [22], filter [23], pulsed tube [24], give auxilliary [44] power that make progress of flap, this power constitutes sealing force between auxilliary flap [44] and the auxilliary valve seat [46] together with preloading spring [28] to the active force of auxilliary flap [44].Along with system pressure rises, the active force that acts on bellows [34] upper end constantly increases, and auxilliary valve control spring [39] and the compressed numerical value of bellows [34] is increase thereupon also, adjustablely constantly reduces in abutting connection with gap delta.When system pressure rises to a certain pressure P c, adjustablely be closed in abutting connection with gap delta.At this moment, the sealing force between auxilliary flap [44] and the auxilliary valve seat [46] reaches the maximum value (see figure 2).After this along with system pressure increases, the sealing force between auxilliary flap [44] and the auxilliary valve seat [46] reduces rapidly.When system pressure reached the cracking pressure definite value of auxilliary valve, sealing power was reduced to zero.When system pressure increased a minimum again, auxilliary flap [44] just was separated from auxilliary valve seat [46], and water or steam enter pulsed tube [21] from auxilliary opening of valves, flow to the epicoele of piston [8].Because the area of section of piston [8] is times over the effective pressure active area of main valve clack [2].The upper cavity pressure of piston [8] need not rise to system pressure, and the power that acts on piston [8] upper-end surface affacts main valve clack [8] rapidly by main valve stem [4] makes sealing force between main valve clack [2] and the main valve seat [49] from fast zero (see figure 3) of reducing to of maximum value.Main valve clack [2] is opened, the discharge pressure medium, and when system pressure dropped to the closing pressure Pc of auxilliary valve, auxilliary flap [44] was closed, and the epicoele of piston [8] is additional because of dielectric leakage does not have, rapid depressurization.Main valve clack [2] is closed rapidly under the acting in conjunction of entrance cavity internal pressure medium and preloading spring [7], keep sealing, thereby the Safety function of finishing when manual electronic or pneumatic unlatching release control valve [19], comes the autonomous valve entrance cavity to enter the epicoele of piston [8] through pulsed tube, equally can be with main valve clack [2]. back down, the discharge pressure medium, after release control valve was closed, main valve clack [2] was closed, keep sealing, thereby finish release function.

2, background technique

The overall structure types of existing indirect acting type safety valve has three kinds.The positive assembling structure of first integral vertical type is as American Electric Power research institute disclosed indirect acting type safety valve in the Final Report of " PWR Safety and Relief ValveTest Program " EPRI NP-2292 Project V102 in December nineteen eighty-two; It two is whole upside-down mountings, the no leakage safety valve shown in the patent No. 87101900; The third is that main and auxiliary valve branch is arranged and is vertical positive assembling structure, as employed indirect acting type safety valve in 1,000,000 kilowatts of nuclear power station of Germany.

The shortcoming of integral body or the vertical formal dress of split is, makes to start to control be under pressure for a long time high temperature action of medium of the main spring of making usefulness, because the loose distortion of high temperature of spring easily makes the cracking pressure definite value drift of valve.

The shortcoming that whole upside-down mounting adds condensate seal is when safety valve opens jumping discharging high-temperature pressure medium, to make the valve body of main valve be subjected to strong thermal shock, particularly to the heavy wall valve body.Because of the cube of thermal shock stress with the valve body wall thickness is directly proportional, increase along with the valve body wall thickness, the thermal shock stress value increases sharply, the increase of the thermal shock stress limiting valve body wall thickness of not allowing, thus limited the increase of discharge capacity of valve and the raising of working medium temperature.

3, summary of the invention

New-type safety valve provided by the invention, as shown in Figure 1, main and auxiliary valve is provided with structure for separating.The vertical formal dress of main valve, auxilliary valve upside-down mounting between the major-minor valve, by pulsed tube [21], [22], [24], release control valve [19], filter [23] etc., is connected together, by fixing clamp [29] clamping at one.Major-minor valve is no leakage safety valve.

The general structure of New-type safety valve provided by the invention, compared with prior art, several tangible advantages are arranged: there are not thermal shock problem in the structural type of whole relatively upside-down mounting condensate seal, main valve body.The increase of the valve body wall thickness that increasing brought of the temperature of working medium and discharge amount is unrestricted: the structural type that the vertical formal dress of relative integral body or split is arranged, auxilliary valve avoids high-temperature pressure medium to starting to control the long-term heating of the main spring of making usefulness because of upside-down mounting, makes spring avoid the loose distortion of high temperature.

As everyone knows, steam, particularly hydrogen, its relative water, much easier by sealing face leakage, owing to making the sealing surface of valve quicken cavitation, the leakage of steam or hydrogen destroyed, and often put to death the working life in sealing surface the working life of valve.As shown in Figure 1, the upper end of the main valve clack in the main valve [2] is a cup-like structure, the problems referred to above have been solved well, experiment shows, because the result that the cross-ventilation in the main valve outlet plenum of safety valve conducts heat, the self-temperature of main valve seat as shown in Figure 1 [49] and main valve clack [2] is lower than the steam temperature in the entrance cavity, the surface that steam touches main valve seat [49] and main valve clack [2] just is condensed into water, make the upper end of main valve clack [2] fill with water with fixed attention, coagulate water seal and live the junction of two sealing surfaces of main valve clack [2] and main valve seat [49], make steam particularly hydrogen be difficult for leaking by sealing surface, the appearance of this structural type, do not have the safety valve of condensate seal with present all formal dress and compare,, be significant improving the working life of sealing surface.

The auxilliary valve of New-type safety valve provided by the invention is an inverted structure, and as shown in Figure 1, it makes bellows [34] and control spring [39] avoid the heating of high-temperature pressure medium, is in the temperature approaching with environment facies for a long time.There is not the loose problem on deformation of high temperature, bellows [34] and control spring [39] because of rigidity not with changing service time, thereby cracking pressure definite value, remain unchanged for a long time, and do not have drifting problem, use adjustable list in abutting connection with the gap delta value, as shown in Figure 1 in addition, by screwing in adjusting screw [38], can make in abutting connection with the gap delta value and strengthen.If the rigidity of control spring [39] is λ 1, the rigidity of bellows [34] is λ 2, the rigidity of preloading spring [28] is λ 3, the Lift of auxilliary valve is h, and auxilliary valve opening pressure is Po, and closing pressure is Pc, the effective pressure area of bellows [34] is Ab, effective sealing area of auxilliary valve seat [46] is Ad, and external pressure is P1, and following relation is arranged between them:

(Po-Pc)Ab＝(Po-P1)Ad (1)

δ(λ1+λ2+λ3)+h(λ1+λ2)＝(Po-P1)Ab (2) $h=\frac{(\mathrm{Po}-\mathrm{Pc})\mathrm{Ab}}{\mathrm{\λ}1+\mathrm{\λ}2}---\left(3\right)$

From the above-mentioned relation formula as can be seen, giving under the situation of fixed structure, only the need change is adjustable just can adjust cracking pressure Po value in abutting connection with the gap delta value.It with existing auxilliary valve upside-down mounting adopt two in abutting connection with the gap or three compare in abutting connection with the technology in gap, the auxilliary valve of New-type safety valve provided by the invention, it is much simple that structure is wanted, the reliability height, cost is low.

Be illustrated in figure 1 as and make auxilliary flap [44] that high reseting performance be arranged, adopt the thin rod of taper [45] guide-localization, because of the guide-localization rod is a carefully rod of taper, radially the heat expansion amount is little, can make the total backlash between the thin rod of auxilliary flap [44] and taper [45] do very for a short time, auxilliary in addition flap [44] can swing, and makes auxilliary flap [44] have very high resetting property.Sealability is improved greatly.

Usually,, how to stretch out a rod, insert in the valve seat, use as the guide-localization of flap at the flap center as daily being seen hand hydraulic pressure pump check valve and other all valves.

As High Temperature High Pressure flap sealing surface, need the anti-corrosion refractory alloy of build-up wear-resistant, stretch out thin rod in the little flap, be unfavorable for flap end face pile-up welding hard alloy, facts have proved that the survival rate of built-up welding is low, the cost height.

The present invention acts in a diametrically opposite way, and has improved the survival rate of auxilliary flap sealing surface weld deposit cemented carbide greatly, and has been convenient to manufacturing, greatly reduces manufacture cost.

As shown in Figure 1, filter provided by the invention [23] as shown in Figure 4, it is the capture type filter, but the immobilized particles thing in its filter pressure medium, the particulate matter filling in case filter screen [d] all is fixed, pressure medium can pass through from the annular gap between filter bowl tube [e] and upper shell [f] and the lower shell body [a], is unlikely because of filter screen stops up fully, and pressure medium cannot get through and causes auxilliary flap to open.

Secondly, the external static seal of auxilliary valve as shown in Figure 1, by delta ring sealing gasket circle [42] being set in the outside of pressure-bearing sleeve [40] and the inboard of auxilliary valve body [30], its lower end contacts with clamping cylinder [41], the upper end of spring strut [37] is spun on the auxilliary valve body [30] in the mode that is threaded, screwing of it can be pushed clamping cylinder [41], seal washer [42] is close on pressure-bearing sleeve [40] and the auxilliary valve body [30], under the effect of pressure medium, make pressure-bearing sleeve [40] further push delta ring sealing gasket circle [42], make it play good seal action.

4, description of drawings

Fig. 1 is the overall construction drawing of New-type safety valve provided by the invention.The main and auxiliary valve of this valve is the apart arrangement structure, the vertical formal dress of main valve (being the below that the main valve clack [2] of main valve is positioned at piston [8]), auxilliary valve upside-down mounting (promptly the auxilliary flap [44] of auxilliary valve is positioned at the top of control spring [39]).Between the major-minor valve, be connected together by pulsed tube [21], [22], [24] release control valve [19], filter [22] etc., by fixing clamp [29] clamping at one.

Fig. 2 represents that the auxilliary flap sealing force of New-type safety valve increases with the increase of system pressure, is dropped rapidly to the sealing characteristics curve of cracking pressure Po during to closing pressure Pc point.

Fig. 3 represents New-type safety valve main valve clack and two kinds of different sealing characteristics curves that occur inverse variation with the sealing force of bore Direct spring loaded safety valve flap with the system pressure variation.

Fig. 4 represents the capture type filter, and filter screen [d] is arranged at filter bowl tube [e] bottom, and the outer and upper shell [a] of filter bowl tube [e] forms annular gap between the lower shell body [f], and fluid also can flow to outer pipe from inlet duct through annular gap.

5, embodiment

New-type safety valve provided by the invention, the structure of main valve are shown in the left part of Fig. 1, and main valve seat [49] is welded on the main valve body [1], and main valve clack [2] is topped on main valve seat [49].The lower end of main valve stem [4] makes it link to each other with main valve clack [2] by the screw-in of plug screw [3], and piston [8] is passed in the upper end, with nut [10], adds locking spring washer [9] and twists solid on piston [8].Piston [8] places cylinder liner [5].Main valve preloading spring [7], place the groove of cylinder liner [5], the upper end contacts with piston [8], the lower end contacts with the bottom of the groove of cylinder liner [5], and being subjected to a certain degree compression, the power that compression is produced passes to main valve clack [2] by piston rod [4], make main valve clack [2] produce an initial impacting force to main valve seat [49], cylinder liner [5] places the epicoele of main valve body [1] from top to bottom.Piston [8] contacts with cylinder liner [5] by piston ring [11], and keeps sealing.Sealing cover [12] places in the epicoele of cylinder liner [5], between sealing cover [12] and cylinder liner [5], be provided with delta ring sealing gasket circle [13], delta ring sealing gasket circle [13] upper end contacts with clamping cylinder [14], jam nut [15] is twisted solid upper end in main valve body [1], by screwing of it, apply pressure to clamping cylinder [14].Delta ring sealing gasket circle [13] makes it closely contact with cylinder liner [5] with sealing cover [12] under the effect of clamping cylinder [14], keeps sealing.Screwing of pre-load nut [16] by friction top [15] upper end makes sealing cover [12] tension in addition, further applies pressure to delta ring sealing gasket circle [13].Gland nut [17] is threaded onto on the sealing cover [12], takes over [18] by sphere and is connected with pulsed tube [21], makes the epicoele that can enter piston [8] from the pressure medium of pulsed tube [21] unblockedly.

Auxilliary valve arrangement is shown in the right part of Fig. 1, auxilliary valve seat [46] places auxilliary valve body [30], and impose seal weld, auxilliary valve seat [46] is connected with auxilliary valve body [30], the center of auxilliary valve seat [46] embeds the thin rod of taper [45], as the guide-localization usefulness of auxilliary flap [44], auxilliary flap [44] is enclosed within on the thin rod of taper [45], and the lower end contacts with preloading spring [28].The lower end of preloading spring [28] contacts with bellows plug [33], and makes its compression, its power pass to auxilliary flap [44], constitutes the impacting force between auxilliary flap [44] and the auxilliary valve seat [46].The lower end that the upper end part of control spring seat [35] is inserted bellows plug [33], adjusting screw [38] screws in from the tapped hole of the lower end of spring strut [37], and holddown spring lid [36], spring cup [36] pressure-controlled spring [39], power is passed to spring lower seat [35], in succession power is passed to bellows plug [33].The upper end of bellows plug [33], by rivet [32] be connected urceolus [25], connect inner core [31] Joint, the two ends clamping of horizontal bolt [26] that passes auxilliary flap [44] transverse holes is between the socket that connects urceolus [25] interior edge face and connection inner core [31].Urceolus [25] moves up and down and mobile with connecting, and to change in abutting connection with the gap delta value, bellows [34] is nested with on bellows plug [33], and weld mutually with bellows plug [33] upper end, and weld mutually with pressure-bearing sleeve [40] lower end.The upper end of pressure-bearing sleeve [40] is provided with adjusting washer (disk) [43] to adjust the upper-lower position of pressure-bearing sleeve [40].The outside of pressure-bearing sleeve [40] is provided with delta ring sealing gasket circle [42], its lower end contacts with clamping cylinder [41], the upper end of spring strut [37] is spun on the auxilliary valve body [30] in the mode that is threaded, its rotation, can compress clamping cylinder [41], seal washer is close on pressure-bearing cover [40] and the auxilliary valve body [30], to keep sealing.The auxilliary mode of valve body [30] to be threaded, put to connect and chewed lid [48], add sealing gasket [47] therebetween, add sealing melting welding, pulsed tube [21] is chewed lid [48] and is welded mutually with connecing, the inlet of pulsed tube [22], filter [23], pulsed tube [24] and auxilliary valve body [30], polyphone welds together, and the entrance cavity of auxilliary valve body [30] is connected with the entrance cavity of main valve body [1].The structure of filter shown in Figure 1 [23] sees Fig. 4 for details, and upper shell [f] welds together with lower casing [a].Supporting base [b] inserts in the lower shell body [a], filter screen [d], supports orifice plate [c] and place on the supporting base [b] therebetween, filter bowl tube [e] is threaded onto on the supporting base [b] in the mode that is threaded, and press filter screen [d] in supporting on the orifice plate [c], its vertical formal dress, upper shell [f] is last, lower shell body [a] is following, and pressure medium flows through filter from top to bottom.

Claims (4)

1. New-type safety valve, it comprises the main valve of vertical formal dress, the auxilliary valve of upside-down mounting and pulsed tube [21], [22], [24], string has release control valve [19] therebetween, filter [23], it is characterized in that main valve stem [4] is fixed between main valve clack [2] and the piston [8], piston [8] epicoele external sealed is adopted sealing cover [12], add delta ring sealing gasket circle [13], by screwing of jam nut [15] that are connected threadably with valve body [1] upper end, delta ring sealing gasket circle [13] can be compressed through clamping cylinder [14], the upper end of sealing cover [12] is connected in the mode that is threaded with pre-load nut [16], screw pre-load nut [16], can further compress delta ring sealing gasket circle [13]; The center of the auxilliary valve seat [46] of auxilliary valve is embedded with the thin rod of a taper [45], auxilliary flap [44] is that the guide-localization rod contacts with auxilliary valve seat [46] with the thin rod of taper [45], the horizontal bolt [26] of clamping on connecting urceolus [25] and being connected inner core [31], it is adjustable in abutting connection with gap delta that lower end surface and being fixed on constitutes between the summit of the knob nail [27] in auxilliary flap [44] lower end, connect urceolus [25] and be connected inner core [31], by rivet [32] and bellows plug [33] Joint, the thin portion of control spring seat [35] upper end inserts in the hole of bellows plug [33] lower end, control spring [39] be enclosed within spring seat [35] around, its lower end contacts with spring cup [36], adjusting screw [38] upper end that screws in spring strut [37] contacts with spring cup [36], bellows [34] is enclosed within the outside of bellows plug [33], be in the inside of pressure-bearing sleeve [40], pressure-bearing sleeve [40] is static seal externally, it is added with triangle seal washer [42] between the inboard of the outside of pressure-bearing sleeve [40] and auxilliary valve body [30], the lower end of delta ring sealing gasket circle [42] contacts with clamping cylinder [41], the upper end of spring strut [37] is spun on the auxilliary valve body [30] with thread connecting mode, the rotation of spring strut [37], can push clamping cylinder [41], delta ring sealing gasket circle [42] is close on pressure-bearing sleeve [40] and the auxilliary valve body [30], pressure medium is to the effect of pressure-bearing sleeve [40], can make delta ring sealing gasket circle [42] more be close to the self-fastening sealing structure that pressure-bearing sleeve [40] and auxilliary valve body [30] are kept sealing.

2. according to the described safety valve of claim 1, the sealed end that it is characterized in that main valve clack [2] is a cup-like structure, can contain condensed water, and condensed water is enclosed in the junction of the sealing surface of the sealing surface of main valve clack [2] and main valve seat [49].

3. according to the described safety valve of claim 1, it is characterized in that the center of auxilliary valve seat [46] is embedded with the thin rod of taper [45], its lower end is taper, and it and auxilliary flap [44] are located and formed small top and big bottom ring-type tapered gaps between the hole, garden.

4. according to the described safety valve of claim 1, it is characterized in that filter [23], constitute the ring-type through-flow gap between its filter bowl tube [e] and upper shell [f] and the lower shell body [a], make it totally become a capture type filter.

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